Locations:
Vivec - Stand at the north end of the Temple canton facing the door to the Hall of Wisdom. From there, turn and face east. Run around the corner. The door is right there.
Balmora - It's on the south wall, between the silt strider port and the Odai.
This was designed to fit in with the game as much as possible and to be at least somewhat role-play friendly and also as lore-friendly as possible. Whether it is or not is arguable, but that is what imagination is for.
Please see Read Me for more details. If you already use Provincial Bath Shoppe mod by Korana, you just need the .esp file. If you don't, install everything included in the .zip file.
DOWNLOAD LINKS:
http://fortelderscrolls.freeforums.org/temple-bath-houses-t125.html
http://download.fliggerty.com/download-15-787
http://morrowind.nexusmods.com/mods/42400/
Enjoy!